#include <bits/stdc++.h>
#define fi first
#define se second
#define pb push_back
#define sz(a) (int)a.size()
#define all(a) a.begin(),a.end()
#define rep(i,n) for(int i=0;i<n;i++)
#define crep(i,x,n) for(int i=x;i<n;i++)
#define drep(i,n) for(int i=n-1;i>=0;i--)
#define vec(...) vector<__VA_ARGS__>
#define _32bB6rn ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0)
using namespace std;
typedef long long ll;
typedef long double ld;
using pii=pair<int,int>;
using vi=vector<int>;
using dq=deque<int>;
int main(){
_32bB6rn;
int n;
cin>>n;
vi a(n);
rep(i,n) cin>>a[i];
sort(all(a));
auto g=[](dq up,dq dw){
if(!sz(up) or !sz(dw)) return;
int diff=0;
if(sz(up)>=2) diff=up[1]-up[0];
crep(i,2,sz(up)){
if(up[i]-up[i-1]!=diff){
return;
}
}
diff=0;
if(sz(dw)>=2) diff=dw[1]-dw[0];
crep(i,2,sz(dw)){
if(dw[i]-dw[i-1]!=diff){
return;
}
}
cout<<sz(up)<<"\n";
for(auto x : up){
cout<<x<<" ";
}
cout<<"\n";
cout<<sz(dw)<<"\n";
for(auto x : dw){
cout<<x<<" ";
}
cout<<"\n";
exit(0);
};
rep(msk,1<<n){
dq up,dw;
rep(i,n){
if(msk&(1<<i)) up.pb(a[i]);
else dw.pb(a[i]);
}
g(up,dw);
}
cout<<"-1\n";
//
return 0;
}
